Simplified numerical modeling and analysis of electrolyte behavior in multiple physical fields for lithium-ion batteries

Abstract

The electrolyte plays an important role in lithium-ion batteries, affecting their state and safety. However, the internal states of the electrolyte in the battery full domain are not easy to obtain directly. The electric field distribution, to which less attention has been paid, is as important as the concentration distribution, even related to battery safety. In this paper, an accurate and real-time simplified model for electrolyte is developed at the mesoscale, based on the Nernst-Planck equation and the continuum equation with some simple and reasonable assumptions. The analytical solutions of steady-state distribution for concentration and electric fields are obtained by theoretical derivation. Then, based on the assumption of internal uniformity of electrode, the numerical solution of the transient-state process is derived under full working conditions. The potential distribution and the overpotentials within electrolytes can be further calculated. Finally, the accuracy of the developed model is verified by the experiment of constant current terminal voltage and the accurate finite volume method. Besides, simulations are carried out to analyze the effects on the variables of electrolytes by varying the parameters in the model. The design suggestions of electrolyte concentration, thickness and porosity of each component in the battery are given.